Plasma chamber

ABSTRACT

A plasma chamber comprising a lower electrode and an upper electrode, and used for dry-etching an LCD, comprises a main power supply comprising a main power source to generate a main voltage having a predetermined main frequency, and a first impedance matching circuit to impedance-match the main voltage; a bias power supply comprising a bias power source to generate a bias voltage having a predetermined bias frequency, and a second impedance matching circuit to impedance-match the bias voltage; and a mixer connected to both the first impedance matching circuit and the second impedance matching circuit, receiving and mixing the main voltage and the bias voltage, and outputting the mixed voltage to one of the lower electrode and the upper electrode. With this configuration, the present invention provides a plasma chamber in which etching conditions such as an etching rate, an etching profile, a selection ratio, etc. are precisely adjusted.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Patent ApplicationNo. 2003-38023, filed Jun. 12, 2003, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a plasma chamber, and moreparticularly, to a capacitively coupled plasma (CCP) chamber for dryetching.

[0004] 2. Description of the Related Art

[0005] In a process of manufacturing a liquid crystal display (LCD), acapacitively coupled plasma (CCP) method, an inductively coupled plasma(ICP) method, etc. are being used to form plasma. Particularly, the ICPmethod that uses an inductive electromagnetic field by generating plasmais widely used because it is possible to form high-density plasma and itis easy to control ion energy by using bias power. On the other hand,the CCP method forms low-density plasma as compared with the ICP method,but is also widely used for etching because it has advantages of asimple equipment, etc.

[0006]FIG. 1 schematically shows a conventional dry etching apparatususing the capacitively coupled plasma.

[0007] As shown in FIG. 1, a dry etching apparatus 100 comprises a CCPplasma chamber 110, and a main power supply 120.

[0008] The CCP plasma chamber 110 comprises a receptor 111, a lowerelectrode 112 and an upper electrode 113.

[0009] The receptor 111 is placed in an inside lower part of the CCPplasma chamber 110 and supports a panel to which photosensitive materialis applied for etching. The lower electrode 112 contacts a bottom of thereceptor 111 and supplies power to the receptor 111. The upper electrode113 is placed in an inside upper part of the CCP plasma chamber 110 andis grounded as a reference electrode with respect to the lower electrode112.

[0010] The main power supply 120 comprises a main power source 121 andan impedance matching circuit 122.

[0011] The main power source 121 supplies alternating current (AC) powerhaving predetermined frequency and predetermined amplitude, and isconnected to the lower electrode 112. The impedance matching circuit 122is electrically connected between the lower electrode 112 and the mainpower source 121, and prevents the AC power supplied from the main powersource 121 from being reversed at the lower electrode 112.

[0012] With this configuration, the conventional dry etching apparatus100 is operated as follows.

[0013] First, a reaction panel is put on the receptor 111. Then, nearlyall gases are evacuated from the CCP plasma chamber 110 by a vacuum pump(not shown) through an exhaust hole (not shown), thereby vacuumizing theCCP plasma chamber 110. Then, a reaction gas is fed into the CCP plasmachamber 110 through an introduce hole (not shown).

[0014] After completing preparation for an etching process, the AC poweris supplied and the etching process is started.

[0015] When the AC power is supplied to the lower electrode 112 from themain power source 121, a time-varying electric field is generatedbetween the lower electrode 112 and the upper electrode 113. Suchtime-varying electric field resolves the reaction gas into an ion, anegative electric charge and a radical. Here, the ion physicallycollides with and chemically reacts to a thin film of the reaction panelby electric force, and the radical physically collides with andchemically reacts to the thin film of the reaction panel by diffusion,thereby etching the reaction panel. Particularly, in the case ofresponsive ion etching (IRE), anisotropic etching is performed accordingto the electric field because the ion is accelerated by the electricfield and collides with the thin film.

[0016] However, in the conventional dray etching apparatus 100, a biaselectric field for the etching varies according to the amplitude and thefrequency of the main power source 121. Thus, there is a limit toprecisely control etching conditions such as an etching rate, an etchingprofile, a selection ratio, etc.

SUMMARY OF THE INVENTION

[0017] Accordingly, it is an aspect of the present invention to providea plasma chamber in which etching conditions such as an etching rate, anetching profile, a selection ratio, etc. are precisely adjusted.

[0018] Additional aspects and/or advantages of the invention will be setforth in part in the description which follows and, in part, will beobvious from the description, or may be learned by practice of theinvention.

[0019] The foregoing and/or other aspects of the present invention areachieved by providing a plasma chamber comprising a lower electrode andan upper electrode, and used for dry-etching an LCD, comprising: a mainpower supply comprising a main power source to generate a main voltagehaving a predetermined main frequency, and a first impedance matchingcircuit to impedance-match the main voltage; a bias power supplycomprising a bias power source to generate a bias voltage having apredetermined bias frequency, and a second impedance matching circuit toimpedance-match the bias voltage; and a mixer connected to both thefirst impedance matching circuit and the second impedance matchingcircuit, receiving and mixing the main voltage and the bias voltage, andoutputting the mixed voltage to one of the lower electrode and the upperelectrode.

[0020] According to an aspect of the invention, the plasma chamberfurther comprises at least one auxiliary power supply comprising anauxiliary power source to generate an auxiliary voltage having apredetermined frequency, and an auxiliary impedance matching circuit toimpedance-match the auxiliary voltage, wherein the mixer is connected tothe auxiliary impedance matching circuit of the auxiliary power supply,receives and mixes the main voltage, the bias voltage and the auxiliaryvoltage, and outputs the mixed voltage to one of the lower electrode andthe upper electrode.

[0021] According to an aspect of the invention, the mixer outputs themixed voltage by adding the received voltages.

[0022] According to an aspect of the invention, the bias frequency islower than the main frequency.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other aspects and advantages of the present inventionwill become apparent and more readily appreciated from the followingdescription of the embodiments, taken in conjunction with the accompanydrawings of which:

[0024]FIG. 1 is a schematic view of a conventional dry etching apparatususing capacitively coupled plasma; and

[0025]FIG. 2 is a schematic view of a dry etching apparatus usingcapacitively coupled plasma according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] Reference will now be made in detail to the embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

[0027]FIG. 2 schematically shows a dry etching apparatus usingcapacitively coupled plasma according to an embodiment of the presentinvention.

[0028] As shown in FIG. 2, a dry etching apparatus 1 comprises a CCPplasma chamber 10, and a power supply 20.

[0029] The CCP plasma chamber 10 comprises a receptor 11, a lowerelectrode 12 and an upper electrode 13. The receptor 11 is placed in aninside lower part of the CCP plasma chamber 10 and supports a reactionpanel to which photosensitive material is applied for etching. The lowerelectrode 12 contacts a bottom of the receptor 11. The upper electrode13 is placed in an inside upper part of the CCP plasma chamber 10 and isgrounded as a reference electrode with respect to the lower electrode12.

[0030] The power supply 20 comprises a main power supply 30, a biaspower supply 40, and a mixer 50.

[0031] The main power supply 30 comprises a main power source 31, and afirst impedance matching circuit 32. The main power source 31 suppliesalternating current (AC) power having a predetermined angular frequency(ω₁) and a predetermined amplitude (E₁), and is connected to the mixer50. The first impedance matching circuit 32 is connected between themixer 50 and the main power source 31, and prevents the AC powersupplied from the main power source 31 from being reversed at the mixer50.

[0032] The bias power supply 40 comprises a bias power source 41, and asecond impedance matching circuit 42. The bias power source 41 suppliesalternating current (AC) power having a predetermined angular frequency(ω₂) and a predetermined amplitude (E₂), and is connected to the mixer50. Here, the lower the frequency is, the heavier a particle reacts thefrequency. Therefore, the angular frequency (ω₁) of the bias powersource 41 causing an ion to collide with the reaction panel ispreferably lower than the angular frequency (ω₁) of the main powersource 31.

[0033] The second impedance matching circuit 42 is connected between themixer 50 and the bias power source 41, and prevents the AC powersupplied from the bias power source 41 from being reversed at the mixer50.

[0034] The mixer 50 receives the AC powers from the main power source 31of the main power supply 30 and the bias power source 41 of the biaspower supply 40, respectively, and outputs a predetermined mixed ACpower to the lower electrode 12. The mixer 50 is provided to prevent themain power source 31 and the bias power source 41 from being directlyconnected to the lower electrode 12 to supply mutually AC power to bothsources. Herein, the mixer 50 mixes the respective AC powers from themain power source 31 and the bias power source 41 by an operation suchas addition. In this embodiment, the addition is used for mixing the ACpower, but it should be appreciated that other operation is applicable.

[0035] A voltage (Vo) outputted from the mixer 50 to the lower electrode12 is as follows.

Vo=E ₁cos(ω₁ t)+E ₂cos(ω₂ t)  <Equation 1>

[0036] In the case where the angular frequency (ω₁) of the main powersource 31 is much larger than the angular frequency (ω₂) of the biaspower source 41, <Equation 1> approximates to the following <Equation2>.

Vo=E ₁ cos (ω₁ t)+E ₁+(E ₂ −E ₁) cos (ω₂ t), where ω₁>>ω₂<Equation 2>

[0037] The voltage (Vo) applied to the lower electrode 12 includes “E₁cos(ω₁t)” employed in generating plasma, and “E₁+(E₂−E₁)cos(ω₂t)”employed in adjusting etching conditions.

[0038] Such voltage for adjusting the etching conditions may be achievedby supplying at least one auxiliary power having a predeterminedfrequency and a predetermined amplitude, thereby more preciselycontrolling the etching.

[0039] For example, the main power supply 30 supplies a main powerhaving a frequency of 13.56 MHz, and separately the bias power supply 40supplies a bias power having a frequency of several MHz˜several hundredkHz. Here, the mixer 50 is employed for preventing a reverse currentwhich may be generated when the powers having the different frequenciesfrom each other are coupled, and for supplying the main power and thebias power at the same time.

[0040] With this configuration, the dry etching apparatus 1 according toan embodiment of the present invention is operated as follows.

[0041] First, the reaction panel to which photosensitive material isapplied is put on the center of the receptor 11. Then, the CCP plasmachamber 10 is vacuumized, and a reaction gas is fed into the CCP plasmachamber 10. Then, the reaction gas is changed into the plasma by themain power source 31 and the bias power source 41 of the power supply20. Then, the ion is accelerated by the electric field and collides witha thin film of the reaction panel, wherein a part of the thin film towhich the photosensitive material is not applied is etched by the ion.

[0042] According to an aspect of the invention, the frequency and theamplitude of the bias power can vary to adjust the etching conditionssuch as an etching rate, an etching profile, a selection ratio, etc.,keeping density of the plasma.

[0043] As described above, the present invention provides a plasmachamber in which etching conditions such as an etching rate, an etchingprofile, a selection ratio, etc. are precisely adjusted.

[0044] Although a few embodiments of the present invention have beenshown and described, it will be appreciated by those skilled in the artthat changes may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe appended claims and their equivalents.

What is claimed is:
 1. A plasma chamber comprising a lower electrode andan upper electrode, and used for dry-etching an LCD, comprising: a mainpower supply comprising a main power source to generate a main voltagehaving a predetermined main frequency, and a first impedance matchingcircuit to impedance-match the main voltage; a bias power supplycomprising a bias power source to generate a bias voltage having apredetermined bias frequency, and a second impedance matching circuit toimpedance-match the bias voltage; and a mixer connected to both thefirst impedance matching circuit and the second impedance matchingcircuit, receiving and mixing the main voltage and the bias voltage, andoutputting the mixed voltage to one of the lower electrode and the upperelectrode.
 2. The plasma chamber according to claim 1, furthercomprising at least one auxiliary power supply comprising an auxiliarypower source to generate an auxiliary voltage having a predeterminedfrequency, and an auxiliary impedance matching circuit toimpedance-match the auxiliary voltage, wherein the mixer is connected tothe auxiliary impedance matching circuit of the auxiliary power supply,receives and mixes the main voltage, the bias voltage and the auxiliaryvoltage, and outputs the mixed voltage to one of the lower electrode andthe upper electrode.
 3. The plasma chamber according to claim 1, whereinthe mixer outputs the mixed voltage by adding the received voltages. 4.The plasma chamber according to claim 2, wherein the mixer outputs themixed voltage by adding the received voltages.
 5. The plasma chamberaccording to claim 1, wherein the bias frequency is lower than the mainfrequency.
 6. The plasma chamber according to claim 2, wherein the biasfrequency is lower than the main frequency.